#!/bin/sh

# Script writen by Daniel Jakots

# First we go through the list of neighbor and we write all the peer and
# their status in "${_TMPDIR}"/bgp-status.

# Then we monitor if this file has changed between now and the previous run.

# If it did, we send a mail with the states of the different sessions.

set -u

PATH=$HOME/bin:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:.

_MAILTO="{{ bgp_mailto }}"
_TMPDIR=/tmp/check-bgp
_PIDFILE="${_TMPDIR}"/bgpd-check-peers.pid


if [ -e /etc/realname ]; then
    _REALNAME=$(cat /etc/realname)
    _HOSTNAME=$(hostname -s)
else
    _HOSTNAME=$(hostname)
fi

mkdir -p "${_TMPDIR}"

# Don't try to run if it's already running
if [ -e "${_PIDFILE}" ]; then
    echo "$(date)" >> "${_TMPDIR}"/log
    exit 1
else
    echo $$ >> "${_PIDFILE}"
fi

# Create an history
if [[ -f "${_TMPDIR}"/bgp-status ]] ; then
    mv "${_TMPDIR}"/bgp-status "${_TMPDIR}"/bgp-status.old
else
    touch "${_TMPDIR}"/bgp-status
    touch "${_TMPDIR}"/bgp-status.old
fi

# List peers and loops on them to list them and their BGP state
bgpctl show neighbor | grep Description {{ bgp_exclude_grep_command }} | sed s,\ Description:\ ,,g > "${_TMPDIR}"/peers-list

while read -r _PEER
do
    _STATUS=$(/usr/sbin/bgpctl show neighbor "${_PEER}" | grep state | awk '{print $4}' |tr -d ',')
    echo -n "${_PEER}" >> "${_TMPDIR}"/bgp-status
    echo -n " " >> "${_TMPDIR}"/bgp-status
    # we note only if it's established or not
    if ! [[ "${_STATUS}" = "Established" ]] ; then
       _STATUS="NotEstablished"
    fi
    echo "${_STATUS}" >> "${_TMPDIR}"/bgp-status

done <"${_TMPDIR}"/peers-list

# Check for difference with previous run
different=$(diff -q "${_TMPDIR}"/bgp-status.old "${_TMPDIR}"/bgp-status)

if ! [[ -n "${different}" ]] ; then
    rm -f "${_PIDFILE}"
    exit 0
fi

# It changed so we're going to send a mail

_TMPMAILDIR="${_TMPDIR}"/mail
mkdir -p "${_TMPMAILDIR}"

# go through sessions and list them depending on their BGP state
echo "*** Session(s) OK ***\n" >> "${_TMPMAILDIR}"/bodyok
while read -r _LINE
do
    # _LINE is session + status
    _STATUS=$(echo "${_LINE##* }")
    _SESSION=$(echo "${_LINE}" | awk '{$NF=""}1')
    if [[ "${_STATUS}" = "Established" ]] ; then
	bgpctl show | grep "${_SESSION}" >> "${_TMPMAILDIR}"/bodyok
    else
	bgpctl show | grep "${_SESSION}" >> "${_TMPMAILDIR}"/bodynok
    fi
done <"${_TMPDIR}"/bgp-status

# create the mail body

echo "Dear NOC,\n\nThe state of one or more BGP session(s) has changed:\n" > "${_TMPMAILDIR}"/header
cat "${_TMPMAILDIR}"/header "${_TMPMAILDIR}"/bodyok > "${_TMPMAILDIR}"/body

_STATE="OK"
if [[ -f "${_TMPMAILDIR}"/bodynok ]] ; then
    _STATE="NOT OK"
    echo "\n*** Session(s) on error ***\n" >> "${_TMPMAILDIR}"/body
    cat "${_TMPMAILDIR}"/bodynok >> "${_TMPMAILDIR}"/body
fi

# show a diff
echo "" >> "${_TMPMAILDIR}"/body
echo "Diff is " >> "${_TMPMAILDIR}"/body
diff -U0 "${_TMPDIR}"/bgp-status.old "${_TMPDIR}"/bgp-status >> "${_TMPMAILDIR}"/body

# Send the mail whether we have a realname or not
if [ -n "${_REALNAME}" ]; then
    cat "${_TMPMAILDIR}"/body | mail -s "[BGP] ${_REALNAME} (${_HOSTNAME}) - State change - ${_STATE}" "${_MAILTO}"
else
    cat "${_TMPMAILDIR}"/body | mail -s "[BGP] ${_HOSTNAME} - State change" "${_MAILTO}"
fi

# cleaning
if [[ -d  "${_TMPMAILDIR}" ]] ; then
    rm -rf  "${_TMPMAILDIR}"
fi
rm -f "${_PIDFILE}"